Fuel injection valve with semicircular flattenings

ABSTRACT

A fuel injection valve includes a valve-closure member which is provided with semicircular flattenings. The deflecting surfaces delimiting the flattenings and formed obliquely to the longitudinal valve axis cause a rotational energy to be applied to the fuel. The application of rotational energy to the fuel makes it possible to clearly reduce the change in flow rate caused by the rotational position of the needle, so that the variance in the static flow rate is considerably decreased. The valve is particularly suitable for application in fuel injection systems of mixture-compressing internal combustion engines having externally supplied ignition.

FIELD OF THE INVENTION

The present invention relates to a fuel injection valve.

BACKGROUND INFORMATION

German Patent Application No. 33 35 169 describes a fuel injectionvalve, in which a spherical valve element having a plurality offlattenings (truncated sections) on its periphery is installed as avalve-closure member to allow fuel to flow around the sphere and thusarrive at the valve seat. The flattenings on the spherical valve-closuremember are needed when the valve-seat body has a complete ring guide forpositioning and aligning the valve-closure member, since otherwise thefuel would dam up at the sphere and not flow through to the valve seat.The flattenings introduced on the periphery of the valve-closure memberare formed in a circular shape and are not spatially associated with thespray-outlet orifices provided on the downstream end of the injectionvalve.

A fuel injection valve having a valve-closure member of a similar designis described in German Patent No. 42 30 376. Here as well, the circularflattenings on the surface area of the spherical valve-closure memberhave the function of allowing fuel to flow out of an inside valve space,into which the valve needle extends, to spray-outlet orifices of theinjection valve. In this case, there is no fixed association between theflattenings on the valve-closure member and the-spray-outlet orifices.On the contrary, the torsional position of the valve needle, and thus ofthe valve-closure member, is arbitrary, and therefore, also varies amongthe individual injection valves of a production series. The flow ofoncoming fuel to the individual (e.g., four) spray-outlet orifices isalso determined by the flattenings.

A spray-outlet orifice is supplied more efficiently with the medium tobe sprayed off when a flattening is situated directly upstream. However,if a guide edge, formed between two flattenings, is located above thespray-outlet orifice, then the result can be that the spray-outletorifice is insufficiently supplied. The irregularity (unevenness) of theoncoming flow in the circumferential direction thus brings about achange in the flow rate and an increased variance in the static flowrate relative to the rotational position of the valve needle.

A fuel injection valve having a spherical valve-closure member (globevalve) is described by U.S. Pat. No. 4,520,962. This valve-closuremember has no means on its periphery for fuel to flow past. On thecontrary, the fuel flows immediately upstream from the valve seat,coming from the side, directly to the valve-closure member. Anadditional spiral member having spiral-shaped grooves is provideddownstream from the valve seat, in which case the grooves apply arotational energy to the fuel. The fuel is then sprayed off through asingle outlet orifice.

Additionally, U.S. Pat. No. 5,199,648 describes a fuel injection valve,in which a valve-closure member that is securely joined to the valveneedle, has a plurality of grooves running at an angle to thelongitudinal valve axis. The depth of the grooves can be constant overthe entire length or be diminished toward the ends of the grooves whilethe deepest spots are in the middle of the grooves. The grooves differfrom the flattenings in that they no longer run only directly on thesurface of the valve-closure member, but have groove bottoms that liemore deeply in the material. In addition to the opening and closing onthe valve seat, the spherical valve-closure member also fulfills thefunction of valve-needle guidance. The grooves serve to allow the mediumto flow through from the inside valve space to the valve seat, arotational energy being applied to the fuel by the angled grooves, and abetter atomization supposedly being achieved. The fuel then emergesdownstream from the valve seat through a centrally arranged spray-outletorifice; thus, it is not distributed among a plurality of spray-outletorifices. The disadvantage of this groove formation is that the totalfuel flowing from the inside valve space to the valve seat is heavilydeflected therein and suffers a loss of pressure, since the grooveseffect a substantial resistance to flow.

SUMMARY OF THE INVENTION

An advantage of the fuel injection valve according to the presentinvention is that in the case of an injection via a plurality ofspray-outlet orifices, for example of an apertured spray disk, the fuelis guided past the valve-closure member in a simple manner so as toallow a nearly equal distribution to the individual spray-outletorifices. The flattenings on the periphery of the valve-closure member,produced according to the present invention by a simple andcost-effective method, guarantee that a nearly unthrottled generation ofrotational (swirling) energy in the fuel, through which means theirregularity of the oncoming flow is evened out in the circumferentialdirection by the rotational position of the valve needle, so that thestatic fuel-flow rate is able to be reproduced considerably better, evengiven very large quantities of fuel injection valves, and remains verystable. The variance in the static flow rate can be restricted to aminimum.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a partial view of an injection valve having circularflattenings on the valve-closure member.

FIG. 2 shows a valve-closure member according to FIG. 1 withspray-outlet orifices projected thereon.

FIG. 3 illustrates a partial view of an injection valve havingsemicircular flattenings on the valve-closure member according to thepresent invention.

FIG. 4 shows a second exemplary embodiment of a valve-closure memberaccording to the present invention.

FIG. 5 shows a third exemplary embodiment of a valve-closure memberaccording to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In a partial view, FIG. 1 illustrates an example of a valve in the formof an injection valve for fuel injection systems of mixture-compressinginternal combustion engines having externally supplied ignition. Theinjection valve has a tubular valve-seat support 1, in which alongitudinal orifice 3 is formed concentrically to a longitudinal valveaxis 2. Arranged in the longitudinal orifice 3 is, for example, atubular valve needle 5, which is joined at its downstream end 6 to aspherical valve-closure member 7, on whose periphery, for example, fivecircular flattenings 8 are provided.

The injection valve is actuated electromagnetically, for example, in agenerally known way. A sketched electromagnetic circuit having asolenoid coil 10, an armature 11, and a core 12 serves to axially movethe valve needle 5 and, thus, to open the injection valve against thespring energy of a restoring spring (not shown) or to close the same.The armature 11 is joined to the end of the valve needle 5 facing awayfrom the valve-closure member 7, for example, by a laser-produced weldand is aligned to the core 12.

A guide opening 15 of a valve-seat member 16 is used to guide thevalve-closure member 7 during axial movement. The cylindrical valve-seatmember 16 is tightly mounted by means of welding in the end of thevalve-seat support 1 situated downstream and facing away from the core12 in the longitudinal orifice 3 running concentrically to thelongitudinal valve axis 2. The circumference of the valve-seat member 16has a slightly smaller diameter than the longitudinal orifice 3 of thevalve-seat support 1. At its lower front end 17 facing away from thevalve-closure member 7, the valve-seat member 16 is concentrically andrigidly joined to a base part 20 of a, for example, pot-shaped aperturedspray disk 21, so that the base part 20 abuts with its upper front end19 on the lower front end 17 of the valve-seat member 16. In its centralarea 24, the base part 20 of the apertured spray disk 21 has at leastone, for example four, spray-outlet orifices 25 formed by means oferosion or punching.

Contiguous to the base part 20 of the pot-shaped apertured spray disk 21is a circumferential retention rim 26, which extends in the axialdirection facing away from the valve-seat member 16 and is bentconically to the outside up to its end 27. Since the circumferentialdiameter of the valve-seat member 16 is smaller than the diameter of thelongitudinal orifice 3 of the valve-seat support 1, a radial compressionexists only between the longitudinal orifice 3 and retention rim 26 ofthe apertured spray disk 21, which retention rim 26 is bent slightlyconically to the outside.

The insertion depth of the valve-seat part comprised of the valve-seatmember 16 and the pot-shaped apertured spray disk 21 into thelongitudinal orifice 3 determines the presetting of the lift of thevalve needle 5, since the one end position of the valve needle 5, givena non-excited solenoid coil 10, is determined by the seating of thevalve-closure member 7 on a valve-seat surface 29 of the valve-seatmember 16. The other end position of the valve needle, given an excitedsolenoid coil 10 is determined, for example, by the fitting of thearmature 11 on the core 12. Thus, the path between these two endpositions of the valve needle 5 represents the lift.

At its end 27, the retention rim 26 of the apertured spray disk 21 isimperviously and securely joined to the inner wall of the longitudinalorifice 3. An impervious connection of the valve-seat member 16 and theapertured spray disk 21, as well as of the apertured spray disk 21 andthe valve-seat support 1 is necessary to ensure that the fuel cannotflow through between the longitudinal orifice 3 of the valve-seat member1 and the periphery of the valve-seat member 16 to the spray-outletorifices 25, or through between the longitudinal orifice 3 of thevalve-seat support 1 and the retention rim 26 of the pot-shapedapertured spray disk 21 directly into a suction line of the internalcombustion engine.

The spherical valve-closure member 7 interacts with the valve-seatsurface 29 of the valve-seat member 16, this valve-seat surface beingtapered in a truncated-cone shape in the direction of flow and beingformed in the axial direction between the guide opening 15 and thebottom front end 17 of the valve seat-member 16. Facing the solenoidcoil 10, the valve-seat member 16 has a valve-seat member opening 34,which has a larger diameter than the diameter of the guide opening 15 ofthe valve-seat member 16. The valve-seat member opening 34 serves as aflow inlet, so that a flow of the medium, such as fuel, can take placefrom an inside valve space 35 delimited in the radial direction by thelongitudinal orifice 3 of the valve-seat support 1 to the guide opening15 of the valve-seat member 16.

To ensure that the flow of the medium also attains the spray-outletorifices 25 of the apertured spray disk 21, five flattenings 8 areintroduced, for example, on the periphery of the spherical valve-closuremember 7. The five circular flattenings 8 enable the medium to flowthrough in the open state of the injection valve from the inside valvespace 35 to the spray-outlet orifices 25 of the apertured spray disk 21.To provide for an exact guidance of the valve-closure member 7 and,thus, of the valve needle 5 during the axial movement, the diameter ofthe guide opening 15 is conceived so as to allow the sphericalvalve-closure member 7, outside of its flattenings 8, to project throughthe guide opening 15 with little radial clearance. There is no fixedassociation between the flattenings 8 on the valve-closure member 7 andthe spray-outlet orifices 25.

FIG. 2 illustrates this situation once again through the use of a blockdiagram (which is not entirely to scale and does not show a directintersection through the injection valve). Rather, to clarify thegeometry, the spray-outlet orifices 25 of the apertured spray disk 21are projected on to the spherical valve-closure member 7.

Since the torsional position of the valve needle 5 relative to thevalve-closure member 7 is arbitrary in each injection valve, differentpositions of the flattenings 8 arise again and again with respect to thespray-outlet orifices 25. The oncoming flow of the fuel to theindividual, for example four, spray-outlet orifices 25, is determined,as well, by the flattenings 8. A spray-outlet orifice 25 is moreefficiently supplied with fuel when a flattening 8 is situated directlyupstream. However, if a guide edge 37 formed between two flattenings 8is located above the spray-outlet orifice 25, then this can result inthe spray-outlet orifice being insufficiently supplied. The resultantunequal distribution of fuel upstream from the apertured spray disk 21inevitably manifests certain instabilities, so that the consequence isan increased variance in the static flow rate through the individualspray-outlet orifices 25 and between the individual injection valves.

One exemplary embodiment of an injection valve according to the presentinvention is shown in a partial representation in FIG. 3, the same partsor the parts having the same function with respect to the injectionvalve shown in FIG. 1 being designated with the same reference numerals.As a special feature, the valve-closure member 7 now only hasflattenings 80, which differ in their shape and geometric dimensionsfrom those already known. The flattenings 80 that are attainable, forexample, by means of milling or grinding on the surface of the sphericalvalve-closure member 7 are designed in a semicircular shape. In thiscase, a deflection surface 41 runs along a bisecting line 40, whichcorresponds to the line of intersection when a complete circle is cutinto two semicircles and, thus, also corresponds to the completecircle's diameter, is not curved, and is not parallel to thelongitudinal valve axis 2. Rather, the deflection surface 41 along thebisecting line 40 obliquely intersects a globe equator 39 runningperpendicularly to the longitudinal valve axis 2, for example, at anangle of 45°, as shown in FIG. 3. The angle between the deflectionsurfaces 41 delimiting the flattenings 80, which can be described asground-down edges for applying a rotational energy (ground-down swirledges), and the ball equator 39 can also deviate from 45°. Thedeflection surfaces 41 run at an angle to the flattenings 80 and extendtoward the ball midpoint.

Thus, the purpose of the flattenings 80 running at an angle to thelongitudinal valve axis 2 is to guarantee that the spray-outlet orifices25 are supplied with fuel and to apply a rotational energy to the fuel.The application of rotational energy to the inner fuel flow of theinjection valve makes it possible to clearly reduce the change in flowrate caused by the rotational position of the needle at the spray-outletopenings 25 and between the individual injection valves, so that incertain types of injection valves, the variance in the static flow rateamounts to just 50% of the variance in the comparable injection valveshaving circular flattenings 8.

It is especially advantageous to form semicircular flattenings 80 on thevalve-closure members 7 when injection valves having so-calledsmall-quantity apertured spray disks are used. Such small-quantityapertured spray disks have, for example, only two spray-outlet orifices25, so that under the state of the art, the torsional position of thevalve needle 5 has a considerable effect on the variance in the staticflow rate. Injection valves, which comprise small-quantity aperturedspray disks having a spray-off fuel volume of 60 to 80 g/min, are ofparticular interest in the case of high-speed, two-stroke internalcombustion engines. It is especially the case for internal combustionengines having a small displacement cubic capacity, for example ofbetween 500 and 1000 cm³, that decisive reductions in the variance ofthe static flow rate and, thus, considerable improvements in thestability of the fuel quantities to be spray-ejected (sprayed off) areable to be achieved due to the flattenings 80 on the valve-closuremember 7 and the resultant swirled inner flow. In the case of aperturedspray disks 21 having spray-off fuel volumes of 150 g/min and more, thedescribed positive effects become especially noticeable when only one ortwo spray-outlet orifices 25 are provided.

The refinement according to the present invention of the semicircularflattenings 80 enables fuel to flow past the valve-closure member 7 overa large surface area without any significant pressure losses resultingfrom a resistance to flow.

FIGS. 4 and 5 depict two additional exemplary embodiments ofvalve-closure members 7 according to the present invention. Thespherical valve-closure members 7 now have two flattenings 80, whichdeviate slightly from a semicircular shape. The deflection surfaces 41do not run, exactly (straight) along the bisecting lines 40 through acomplete circle, but rather in a slightly curved convex or concaveshape. FIG. 4 depicts a valve-closure member 7, which has a convexdeflecting surface 41 that produces a stronger deflection of the fuel.On the other hand, the valve-closure member 7 in FIG. 5 has concavedeflection surfaces 41 on the flattenings 80, so that the fuel isdeflected to a lesser extent. Thus, specific swirl directions are ableto be produced with these specific embodiments.

What is claimed is:
 1. A fuel injection valve for supplying an internalcombustion engine with fuel, the valve having a longitudinal valve axis,comprising:a spherical valve-closure member having a periphery; avalve-seat surface with which the spherical valve-closure memberinteracts, allowing fuel to flow along the longitudinal valve axis,along the valve-closure member; at least one spray-outlet orificedownstream from the valve-seat surface; and a plurality of substantiallysemicircular flattenings on the periphery of the valve-closure member,the flattenings being delimited by at least one deflecting surface whichruns at an angle to the flattenings and runs obliquely to thelongitudinal valve axis.
 2. The fuel injection valve according to claim1, wherein the deflecting surface intersects a globe equator atapproximately 45 degrees, the globe equator running perpendicular to thelongitudinal valve axis.
 3. The fuel injection valve according to claim1, wherein the flattenings are produced by at least one of milling andgrinding.
 4. The fuel injection valve according to claim 1, wherein thedeflecting surface runs concavely toward the flattenings.
 5. The fuelinjection valve according to claim 1, wherein the deflecting surfaceruns convexly toward the flattenings.
 6. The fuel injection valveaccording to claim 1, wherein the flattenings are delimited by aplurality of deflecting surfaces.
 7. A fuel injection valve forsupplying an internal combustion engine with fuel, the valve having alongitudinal valve axis, comprising:a spherical valve-closure memberhaving a periphery; a valve-seat surface with which the sphericalvalve-closure member interacts, allowing fuel to flow along thevalve-closure member in an extension direction of the longitudinal valveaxis; at least one spray-outlet orifice downstream from the valve-seatsurface; and at least one substantially semicircular flattening at theperiphery of the valve-closure member, the flattening being delimited byat least one deflecting surface positioned obliquely to the longitudinalvalve axis.
 8. The fuel injection valve according to claim 7, whereinthe deflecting surface intersects a globe equator running perpendicularto the longitudinal valve axis at an angle approximately equal to 45degrees.
 9. The fuel injection valve according to claim 7, wherein theflattenings are produced by milling or grinding.
 10. The fuel injectionvalve according to claim 7, wherein the deflecting surface runsconcavely toward the flattenings.
 11. The fuel injection valve accordingto claim 7, wherein the deflecting surface runs convexly toward theflattenings.
 12. The fuel injection valve according to claim 7, whereinthe flattening is delimited by a plurality of deflecting surfaces.